Box-type plating rack



July 18 1967 A. H. BEI-JBE, JR., ET AL 3,331,764

BOXTYPE PLATING RACK Filed Feb. 24, 1964 2 Sheets-Sheet l .lilly 1s, 1967 Filed Feb. 24, 1964 A. H. BEEBE, JR.. ET Al- Box-TYPE PLATIN@ RACK 2 Sheets-Sheet 2 ,BFHE/NG D/HMETEI?, INCHES INVENTORS,

United States Patent 3,331,764 BOX-TYPE PLATIN G RACK Austin H. Beebe, Jr., Ann Arbor, and James H. Lake, Whitmore Lake, Mich., assignors to Federal-Mogul Corporation, a corporation of Michigan Filed Feb. 24, 1964, Ser. No. 346,838 6 Claims. (Cl. 204-297) ABSTRACT F THE DISCLOSURE A box-type electroplating rack including a face panel having an elongated slot therealong and wherein the inner surface of the face panel adjacent to the slot is formed with an inwardly extending angular projection of a controlled angularity for providing increased uniformity in the thickness of the plate deposited on the concave surfaces of semi-cylindrical articles which are positioned with their end edges in abutting contact against the inner surface of the face panel and with their concave surfaces disposed symmetrically relative to the slot.

The present invention .broadly relates to electroplating apparatus, and more particularly to an improved boxtype electroplating rack which is particularly suitable for applying a substantially uniform plating on the coucave surfaces of semi-cylindrical workpieces such as precision sleeve or shell-type half bearings or the like.

In the manufacture of precision shell-type half bearings, it is frequently desirable to apply an overplate or lining of a suitable bearing metal on the nished semicylindrical bearing surface to enhance the bearing characteristics thereof. The overplate is `conventionally ap plied in a thickness of from several ten thousandths of an inch to several thousandths of an inch depending on the specific type of bearing and its intended end use. Since the overplate is applied to the semi-cylindrical concave surface which has been preliminar-ily machined to within accurate dimensions, it is desirable to apply the overplate in a uniform manner to avoid any subsequent refinishing operations.

Various types of plating racks have heretofore been used or proposed for use for applying such overplates to the concave semi-cylindrical surfaces of precision shelltype half bearings or corresponding articles having semicylindn'cal concave surfaces. In order to achieve uniformity of the plating deposited over the entire semi-cylindrical surface, plating racks employing a central -anode have been suggested for use but have been found to be unacceptable under operating conditions due to a slight outof-roundness of the anode or a slight eccentric disposition thereof relative to the cylindrical surface to be plated resulting in significant variations in the thickness and in the composition of the overplate applied to different areas of the surfaces to be plated. Additionally, where more than one type of metal is to be plated, racks of this type are inefficient requiring change of anodes between different plating solutions. Racks of this type are also impractical when bagged anodes are necessary.

Alternatively, box-type plating racks have heretofore been employed of the general type as disclosed in U.S. Patent No. 2,697,690, granted Dec. 21, 1954, to A. H. Beebe, Ir., and assigned to the same assignee as the present invention. The electroplating rack as disclosed in the aforementioned patent is adapted to concurrently plate the concave semi-cylindrical surfaces of a column of stacked shell-type half bearings which are supported within an enclosure and which are positioned with the concave surfaces thereof disposed in communication with an elongated slot formed in the face panel of the enclosure. The stacked column of bearings are disposed with their end edges positioned in abutting contact against the rear surface of the face panel and with the concave surfaces thereof in aligned symmetrical relationship relative to the axis of the slot.

In accordance with this relationship, current ows through the slot and into the interior of the enclosure effecting a deposit of a plating on the concave surfaces of the column of bearings. It has been found, however, that in accordance with the construction of the plating rack disclosed in the aforementioned patent that a greater thickness of plating deposits on those areas of the semicylindrical surface adjacent to the crush relief area of the bearing as opposed to the crown of the bearing causing nonuniformity of the thickness of overplate over the semi-cylindrical `bearing surface. Such nonuniformity in overplate thickness detracts from obtaining an optimum fit of the bearing around a shaft journaled therein.

It is accordingly a principal object of the present invention to provide an improved box-type plating rack which overcomes the problems and disadvantages associated with the formation of nonuniform platings on the surfaces of semi-cylindrical articles in accordance with plating racks of the types heretofore known.

Another object of the present invention is to provide an improved box-type plating rack which incorporates a face panel provided with an elongated slot therethrough which is of a controlled shape and size providing thereby unexpected uniformity in the plating thickness deposited over the entire area of semi-cylindrical workpieces.

A further object of the present invention is to provide an improved box-type plating r-ack which is of simple and durable design, of versatile use, and of economical manufacture.

The foregoing and other objects and advantages of the present invention are achieved by a box-like plating rack comprising yan enclosure including a face panel which is formed with an elongated aperture or slot therethrough that extends for substantially the entire length of the panel. The enclosure is provided with suitable clamping means for removably clamping a stacked column of workpieces such as semi-cylindrical shell bearings, for example, which 'are positioned with their end edges in abutting contact with the rear surface of the face panel and with their concave semi-cylindrical surfaces positioned in symmetrical alignment relative to the axis of the slot. The width of the slot is controlled within a range corresponding to about 20% to about 42% of the diameter of the semi-cylindrical concave surfaces and the rearward or inner surface of the panel is formed with an inwardly extending angular projection having a controlled angularity of from about 7 to about, 15 relative to the plane of the inner surface of the face panel and a width ranging from about 12% to about 40% of the diameter of the concave surfaces. The angular projections extend from a point coinciding with the inner edge of the slot laterally therefrom toward the end edges of the semi-cylindrical workpieces. In a preferred form of the present invention and in accordance with the teaching as contained in U.S. Patent No. 2,697,690, the outer surface of the face panel is formed with outwardly diverging Walls adjacent to the slot for increasing the rate of plating deposit on the semi-cylindrical surfaces.

Other objects and advantages of the present invention. will become apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a front elevational view of a box-type plating rack constructed in accordance with the preferred embodiments of the present invention and with portions thereof lbroken away revealing the internal structure of the rack;

FIGURE 2 is a longitudinal vertical sectional view of the rack shown in FIGURE 1 and taken along the Vline 2-2 thereof;

FIGURE 3 is a transverse horizontal sectional view through the plating rack shown in FIGURE 1 and taken along the line 3-3 thereof, and Y FIGURE 4 is a graphical representation ofthe uniformity in the plating obtained on a series of semicylindrical bearings of varying diameter employing the box rack of the present invention in comparison to that obtained on a similar box-type plating rack devoid of the inwardly directed angular projection adjacent to the edges of the slot.

Referring now in detail to the drawings and as may be best seen in FIGURES 1-3, a box-type plating rack exemplary of the types to which the present invention is applicable comprises an enclosure including a pair of side panels 1t) and 12, an upper end panel 14, a lower or bottom end panel 16, a hingedly mounted -rear panel 18, and a face panel 20. The several panels are fabricated of a plastic or other suitable electrically non-conductive material which is of satisfactory strength and resistant to chemical attack by the acidic and alkaline solutions in which it is immersed. The rear edges of the side panels 10, 12, upper panel 14 and bottom panel 16 are provided with a resilient gasket 22 against which the rear panel 1S is adapted to abut when in the closed position restricting the ilow of electrolyte into the interior of the enclosure around the outer surfaces of a stacked column of semicylindrical workpieces such as bearings 24 shown in phantom. The lower or bottom end panel 16 may be provided with one or more apertures or ports 26 as ybest seen inv FIGURE 2, to facilitate drainage of the treating solution or electrolyte from the interior of the rack on its withdrawal from the treating solution. The arrangement and size of the ports 26 and the disposition of the seal 22 are such so as to restrict circulation of the electrolyte and the flow of current to the rear surfaces of the stacked column of bearings 24 preventing any appreciable deposit of a plating on the rear surfaces thereof.

The face panel is formed with a longitudinally extending aperture or slot 28 which extends centrally there- Vof and for substantially the entire length of the face panel. The stacked column of bearings 24 which are illustrated in phantom in FIGURES 2 and 3 are arranged in registered side-edge to side-edge abutting relationship with the lowermost one thereof seated against-the inner Y surface of the bottom end panel 16 and with the uppermost bearing of the Vcolumn disposed in bearing Contact against a Vmovable shoe 30 which is resiliently biased by means of a pair of coil springs 32 into clamping relationship against the upper end of the column of bearings. Y

Thecoil springs 32 as will be noted Vin FIGURE 3, vare positioned in the enclosure to extend between the movable shoe 30 and the bottom end panel 16 exteriorly of the outer surface of the stacked column of bearings. The clamping force applied to the column of bearings by the resiliently biased movable shoe 30 maintains the abutting side edges of adjacent bearings in close contact restricting the passage of current therebetween to the rear surfaces of the bearings. Y Y

In the exemplary embodiment of the rack as shown in the drawings, the rear panel 1S is provided with a series of longitudinally spaced contact springs 34 which are clamped between a conductor rod 36 and the inner sury face of the rear panel18 by means of a series of screws 38. The upper end of the conductor rod 36 may be Y formed with a suitable hook-shaped portion indicated at 4tl'for engaging and suspending the'work rack from a suitable supporting rail which may be electrified with a cathodic current. The contact springs 34 in addition to electrifyingthe stacked column of bearings 24 additionally serve to bias the bearings forwardly assuring firm abutting contact of their end edges with the rear surface of the face panel 20.

4 Access to the interior of the enclosure in the exemplary plating rack illustrated in the drawings is facilitated byV hingedly mounting the rear panel 18 by means of a pair,

`of pins 42 pivotally connecting a pair of ears 44 connected to a projecting end of the rear panel 18 and a pair of lugs 46 securely fastened to the outer surface of the.

side panel 12, as best seen in FIGURE 3. The opposite edge of the rear panel 18 is formed with a pair of slotsY 48 extending inwardly from the edge thereof in which a l pair of pivotally mounted bolts 50 are adapted to be removably disposed and retained therein by means of nuts 52 maintaining thegcover in the closed position duringV transfer of the loaded rack through the several plating stations. It will be understood that the specific construction of the enclosure and the particular means by Vwhich the stacked column of semi-cylindrical workpieces are retained within the enclosure can be varied while still attaining the improved uniformity in the plating Vdeposit on the inner concave surfaces in View of the improved shape of the slot 2S as hereinafter described.

As will -be best seen in FIGURE 3, the elongated slot 28 is formed along its inner surface with an inwardly eX- tending angular projection extending from a point'spaced laterally of the edge of each side of the slot and inwardly and toward the slotterminating at a point coinciding with the edge thereof. In order to attain the benets of the present invention, it is important that the width of the slot indicated at W, the width or length of the angular projecion indicated at L and the angle of theinner surface of the angular projection indicated at A, be carefully controlled within specified limits in order to provide for a A substantially uniform plating deposit over the entire con-V cave surface of the semi-cylindrical workpiece indicated jection is of a controlled angle A relative to the plane of the inner surface of the face panel indicated at 54 in a controlled amount rangingfrom 7 to about' 15 and preferably from about 10 to about 13.

The width W of the slot can be varied within the aforementioned limits to provide the proper current density and plating rate depending on the voltage available. The

angle A will Vvary as aY function of the width of the slot employedY andthe minimum, maximum and preferred relationships have been empirically established in accordance with the following formulae:

A (min.)=5.7 (W) plus 4 A (max.)=2.3 (W) plus 10.6 A (pref'.)=3.55` (W)fpluS 8 the face .panel 2t) that forV any given slot conguration,iY

a range of concave workpieces having surfaces ranging over a selected range of diameters can be satisfactorily plated employing the same plating rack. This feature provides for increased versatility of the present invention while concurrently providing for improved uniformity vof the platings deposited on the surfaces of the concaveV workpieces.

In accordance with another preferred embodiment of the plating rack as shownr in FIGURES l-3 and as fully disclosed in the aforementioned U.S. Patent No. 2,697,- 690, the longitudinal slot 28 is formed with outwardly diver-ging walls indicated at 56 disposed symmetrically relative to the slot 28 and directed outwardly toward the outer surface of the face panel 20. The provision of the outwardly diverging walls as set forth in the aforementioned United States patent provides for a substantial increase in the rate of plating through the slot. It will be appreciated, however, that the provision of the outwardly diverging walls 56 constitutes a preferred embodiment and is not necessary to achieve the improved uniformity of the plating as provided by the inwardly extending angular projections comprising the present invention.

In operation, the plating rack is loaded by unlatching the rear panel 18 and positioning -a series of semi-cylindrical workpieces such as the bearings 24 in symmetrically aligned relationship relative to the slot 28 and with their end edges disposed in abutting contact against the inner surface of the face panel 20. The movable shoe 30 is extended to enable the loading of the bearings and is thereafter released eiecting tight clamping relationship of the column of bearings between the clamping shoe 30 and the inner surface of the bottom end panel 16. The rear panel 18 is thereafter closed and latched by means of the bolts 50 and nuts 52 coacting with the slots 48 in the edge of the rear panel. During the closing of the rear panel, the contact springs 34 resiliently engage the rear surfaces of the stacked column of bearing urging them into firm engaging contact with the inner surface of the face panel 20 and concurrently effecting an electrical contact therewith.

The rack subsequently is loaded on a suitable processing machine and electrification of the workpieces is achieved in accordance with the exemplary embodiment illustrated in the drawings by the flow of current from the conductor rod 36 through the contact springs 34 to the bearings 24. As best seen in FIGURE 3, the rack, when immersed in an appropriate electroplating solution, may be positioned such as, for example, with the slot 28 disposed adjacent to an anode 58 which may be of any desired shape or configuration. The anode 58 preferably is of a length suiiicient to extend for the entire length of the slot 28 although under some circumstances this may not be desired. It is also contemplated that a plurality of anodes such as additional anodes indicated in phantom at 60 may also be employed which may be of the same or different composition.

Electrication of the workpieces while immersed in a plating solution with a cathodic charge and the anode 58 or the anodes 60 with an anodic charge eiects the ow of current from the anodes through the slot 28 to the inner circumferential surfaces of the workpieces. The provision of the inwardly extending angular projections of a size and configuration within the limits hereinbefore specified has been found to provide a substantially uniform plating deposit over the entire area of the concave surface to be plated.

A comparison of the improved uniformity achieved in accordance with the present invention in comparison to the non-uniformity obtained in a plating rack of the type disclosed in U.S. Patent 2,697,690 is graphically illustrated in FIGURE 4. Comparisons of the uniformity of the plating thickness were based on a plating deposit of l mil at the crown of the bearing which corresponds to a point on the semi-cylindrical concave surface disposed directly opposite to the opening of the slot 23, or, in other words, a point spaced 90 from each of the end edges of the bearing 24 disposed in contact against the inner surface of the face panel 20. The thickness of the plating at the crown of the bearing was compared to the plating deposited at the crush-relief area of the bearing which corresponds to a point along the concave surface spaced slightly from the end edges of the bearing in a vicinity indicated at X in FIGURE 3. Conventionally, the plating deposit at the crush-relief are in :box-type plating racks of the types heretofore known has been substantially greater than the plating deposit at the crown of the bearing.

In accordance with the graphical illustration shown in FIGURE 4, variations in the thickness of the plating at the crush-relief area for a iixed plating thickness of l mil at the crown of the bearing are provided for bearings ranging in diameter from about 21/2 inches up to about 41/2 inches. As will be noted in the upper curve of the graph shown in FIGURE 4, which was obtained on a plating rack having a face panel with a flat inner surface and a slot width W of 1%4 inches, the thickness of the plating at the crush-relief area was substantially greater over the range of bearing sizes plated than the plating deposit at the crown. This variation ranged from about 5% for bearing of 41/2 inches in diameter to a variation as high as 35% for bearings of 21/2 inches in diameter. In contrast, employing a plating rack incorporating an improved slot configuration in accordance with the present invention wherein the inward angular disposition of the slot corresponding to angle A was 12 and with a slot width -of 1%4 inch corresponding to the same slot width employed in the iiat plating rack provided a substantially uniform plate thickness over the entire range of bearing sizes plated. The variation as shown was only a 2% decrease in plating thickness at the crush-relief area in comparison to the plating thickness deposited at the crown of the bearing which represents a substantial and significant improvement over the results obtained with the conventional at inner surface plating rack.

It will be appreciated that the improved uniformity in plating thickness over the area of semi-cylindrical concave surfaces is equally applicable to a series of stacked shell-type half bearings as well as to single workpieces of greater length having a semi-cylindrical concave surface regardless of the particular configuration of its outer surface. Only appropriate modifications in the clamping mechanism are required to accommodate alternate workpiece configurations while retaining the improved configuration of the slot.

While it will be apparent that the preferred embodirnents herein illustrated are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation, and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. A box-like plating rack comprising an enclosure including a face panel formed with an elongated slot therethrough, means for removably clamping a column of concave workpieces in said enclosure with the semi-cylindrical concave surfaces thereof disposed in communication with and in symmetrical alignment relative to the axis of said slot and with the end edges thereof positioned in abutting contact against the inner surface of said face panel, said slot extending for substantially the entire length of the column of workpieces and having a width of from about 20% to about 42% of the diameter of the concave surfaces thereof, said inner surface of said face panel formed with an angular projection extending uniformly along the edge of each side of said slot for substantially the entire length thereof, said projection commencing at a point spaced about 12% to about 40% of the diameter of the concave surface from each edge of said slot inwardly at an angle of from about 7 to about 15 to the plane of said inner surface and terminating at a point coinciding with the edges of said slot.

2. A box-like plating rack comprising an enclosure including a face panel formed with an elongated slot therethrough, means for removably clamping a column of concave workpieces in said enclosure with the semi-cylindrical concave surfaces thereof disposed in communication with and in symmetrical alignment relative to the axis of said slot and with the end edges thereof positioned in abutting contact against the inner surface of said face panel, said slot extending for substantially the entire formly along the edge of each of side of said slot for substantially the entire length thereof, said projection commencing at a point spaced about 12% to about 40% of the diameter of the concave surface from each edge of said slot inwardly at an angle of from about 7 to about 15 to the plane of said inner surface and terminating at a point coinciding with the edges of said slot.

3. A box-like plating rack comprising an enclosure including a face panel formed with an elongated slot therethrough, means for removably clamping a column of concave worlgpieces in said enclosure with the semi-cylindrical concave surfaces thereof disposed in communication with and in symmetrical alignment relative to the axis of said slot and with the end edges thereof positioned in abutting contact against the inner surface of said face panel, said slot extending for substantially the entire lengthv of the column of workpieces and having a width of from about 20% to about 42% of the diameter of the concave surfaces thereof, said inner surface of said face panel formed with an angular projection extending uniformly along the edge of each side of said slot for substantially the entire length thereof, said projection commencing at a point spaced about 12% to about 40% of the Y diameter of the concave surface from each edge of said slot inwardly at an angle of from about 10 to about 13 to the plane of said inner surface and terminating at a point coinciding with the edges of said slot.

4. A box-like plating rack comprising an enclosure including a face panel formed with an elongated slot therethrough, means for removably clamping a column of concave workpieces in said enclosure with the semi-cylindrical concave surfaces thereof disposed in communication with and in symmetrical alignment relative to the axis of said slot and with the end edges thereof positioned Y in abutting contact against the inner surface of said face panel, said slot extending for substantially the entire length of the column of workpieces and having a width of from about 28% to about 42% of the diameter of the concave surfaces thereof, said inner surface of said face panel formed with an angular projection extending uniformly along the edge ofV each side of said slot for substantially the entire length thereof, said projection cornniencing at a point spaced about 12% to about 40% of the diameter of the concave surface from each edge of said slot inwardly at an angle of from about 10 toabout 13 to the plane of said inner surface and terminating at a point coinciding with the edges of said slot.

5. A box-type plating rack comprising an enclosure including a face panel formed with an elongated slot therethrough, means for removably clamping a column of concave workpieces in'said enclosure with the semi-cylindrical concave surfaces thereof disposed in communication with and in symmetrical alignment relative to the Y axis of said slot and with the end edges thereof positioned in abutting contact against the inner surface of said face panel, said slot extending for substantially the entire length of the column of workpieces and having a width` of from about 20% Vto about 42% of the diameter of the concave surfaces thereof, said inner surface of said face panel formed Ywith an angular projection extending uni-l formly along the edge of each side of said sl-ot for substantially the entire length thereof, said projection cornmencing at a point spaced about 12% to about 40% of the diameter of the concave surface laterally relative to each edge of said slot and inwardly therefrom toward said slot at an angle of from about 7 to about 157 relative to the plane of said inner surface and terminating at a point coinciding with the edges of said slot, said slot formed adjacent to the outer surface of said face panel with outwardly diverging walls to provide a slot opening Y in said outer surface which is greater than the slot open-V Y ing adjacent to said inner surface.

6. A box-type plating rack comprising an enclosure including a face panel formed with an elongated slot therethrough, means for removably clamping a column of concave workpieces in said enclosure with the semi-cylindrical concave surfaces thereof disposed in .communication with and in symmetrical alignment relative to the axis of said slot and with the end edges thereof positioned in abutting contact against the inner surface of said face panel, said slot extending for substantially the entire length of the column of workpieces and having a width.

of from about 28% to about 42% of the diameter of the concave surfaces thereof, said inner surface of said face panel formed with an angular projection extending uniformly along the edge of each side of said slot for substantially the entire length thereof, said projection commencing at a point spaced about 12% to about 40% of the diameter of the concave surface laterally relative to each edge of said slot and inwardly therefrom toward said slot at an angle of from about 10 to about 13 relative to the plane of said inner surface and terminating at a point coinciding with the edges of said slot, said slot formed adjacentY to the outer surface of said face panel with outwardly diverging walls to provide a slotV opening in said outer surface which is greater than the slot opening adjacent to said inner surface.

References Cited UNITED STATES PATENTS 2,500,206 3/ 1950 Schaefer et al, Y 204-297 2,697,690 12/1954 Beebe 204-297 2,751,340 6/ 1956 Schaefer et al 204-23 

1. A BOX-LIKE PLATING RACK COMPRISING AN ENCLOSURE INCLUDING A FACE PANEL FORMED WITH AN ELONGATED SLOT THERETHROUGH, MEANS FOR REMOVABLY CLAMPING A COLUMN OF CONCAVE WORKPIECES IN SAID ENCLOSURE WITH THE SEMI-CYLINDRICAL CONCAVE SURFACES THEREOF DISPOSED IN COMMUNICATION WITH AND IN SYMMETRICAL ALIGNMENT RELATIVE TO THE AXIS OF SAID SLOT AND WITH THE END EDGES THEREOF POSITIONED IN ABUTTING CONTACT AGAINST THE INNER SURFACE OF SAID FACE PANEL, SAID SLOT EXTENDING FOR SUBSTANTIALLY THE ENTIRE LENGTH OF THE COLUMN OF WORKPIECES AND HAVING A WIDTH OF FROM ABOUT 20% TO ABOUT 42% OF THE DIAMETER OF THE CONCAVE SURFACES THEREOF, SAID INNER SURFACE OF SAID FACE PANEL FORMED WITH AN ANGULAR PROJECTION EXTENDING UNIFORMLY ALONG THE EDGE OF EACH SIDE OF SAID SLOT FOR SUBSTANTIALLY THE ENTIRE LENGTH THEREOF, SAID PROJECTION COMMENCING AT A POINT SPACED ABOUT 12% TO ABOUT 40% OF THE DIAMETER OF THE CONCAVE SURFACE FROM EACH EDGE OF SAID SLOT INWARDLY AT AN ANGLE OF FROM ABOUT 7* TO ABOUT 15* TO THE PLANE OF SAID INNER SURFACE AND TERMINATING AT A POINT COINCIDING WITH THE EDGES OF SAID SLOT. 